The use of plants as medicinal agents has a long and successful history. The majority of medicines used today are either derived directly from plants or synthesized as variations on natural molecules. However, modern medical practice has, for the most part, abandoned the use of whole plant products because of objections concerning variability in concentration of active ingredients, and unpredictable rates of active drug release from orally ingested crude drugs. Even teas made from medicinal plants cannot fully overcome the latter objection, as the dose provided depends on compound solubility and the conditions of extraction. In addition, accurate self-titration of this dose cannot be expected to overcome either objection, considering the excessive time-lag between oral ingestion and the onset of action.
The best resolution of these problems is through pulmonary ingestion of vaporized compounds, if they are sufficiently volatile. This provides a more immediate means of relief and a more accurate method for dose self-titration, as well as allowing a means for applying compounds to the pulmonary tract itself, as is necessary with diseases such as bronchial asthma, etc. Pulmonary ingestion of drugs also circumvents the "first-pass effect" by which oral drugs are transferred from the intestines and then partially or entirely metabolized by the liver, before entering the blood stream.
Unfortunately, the only technique available to accomplish pulmonary application of crude natural drugs has been via the method of smoking. This is objectionable from the medical perspective because pyrolysis products are irritating and long-term ingestion of smoke has been implicated in the etiology of various pulmonary disease states (e.g., emphysema, cancer, etc.).
Other objections to inhalers such as U.S. Pat. No. 87,603 (Tichenot) which continuously heats or pyrolizes a substance on a grating, and U.S. Pat. No. 1,858,580 (Collins) which steam heats a carrying agent permeated with a medicated substance, involve the lack of ability to either maximize the extraction exposure of the specimen particles, or to promote a uniform extraction of the aggregate charge through its periodic mixing. Additionally, prevention of large particle inhalation which may prove irritating to the pulmonary system of the user, and providing a demand-only flow of heated gas upon each inhalation, which spares wasteful loss of active ingredient during periods of device disuse, is not achieved.